magnesium oxide 420 mg Tablet, 100-count
by Marlex Pharmaceuticals Inc. · 100 TABLET in 1 BOTTLE (10135-721-01)
NDC 10135-0721-01
🏷️ FDA NDC (as labeled)
10135-721-01
billing pads the product segment with a zero
OTC
On market
Non-controlled
🗂️ Data synced Sep 17, 2026 · sources: openFDA · FDA label (DailyMed) · FDA Orange & Purple Book · First Databank · CMS NADAC, ASP, Medicare & Medicaid · RxNorm
📋 All sources & update times →
🆔 Identity & classification
FDA NDC (as labeled)
10135-721-01
Product NDC
10135-721
11-digit billing NDC
10135072101
NCPDP billing unit
EA — each (per item)
RxCUI
311430
UNII
3A3U0GI71G
Application #
M001
SPL Set ID
dc57893c-068a-37d8-e053-2a95a90aa054
Established class (EPC)
Calculi Dissolution Agent; Osmotic Activity
Mechanism of action
Magnesium Ion Exchange Activity
Physiologic effect
Increased Large Intestinal Motility; Inhibition Large Intestine Fluid/Electrolyte Absorption; Inhibition Small Intestine Fluid/Electrolyte Absorption
DEA schedule
Non-controlled
Marketing category
OTC MONOGRAPH DRUG
Marketing status
On market
FDA listing status
Listed (active directory)
Marketing start
2023-11-01
Route
ORAL
Dosage form
TABLET
Substance
MAGNESIUM OXIDE
GPI-14
79400010360319
GPI class
Magnesium Oxide
GCN Seq No
001409
GCN
04093
HICL code
000609
Ingredient (HICL)
Magnesium Oxide
HIC1 code
C
Therapeutic class — broad (HIC1)
Electrolyte Balance/Metabolism/Nutrition
HIC2 code
C1
Therapeutic class — intermediate (HIC2)
Drugs Affecting Electrolyte Balance
HIC3 code
C1H
Therapeutic class — specific (HIC3)
Magnesium Salts Replacement
AHFS code
56:04.00.00
AHFS class
Antacids And Adsorbents
FDB label name
MAGNESIUM OXIDE 420 MG TABLET
FDB brand name
Magnesium Oxide
Legend status
Q — Non-drug — dietary supplement, vitamin, medical food, or herbal preparation
Why two NDCs?
The FDA registers this code as 10135-721-01 — a 5-3-2 layout, and that's what's printed on the package and shown on DailyMed. For insurance claims, every NDC is standardized to a uniform 11-digit 5-4-2 format by adding a zero to the product segment → 10135-0721-01. Same drug, same package — only the format differs.
Where does this data come from?
Identifiers from the FDA openFDA NDC Directory and Structured Product Labeling; RxCUI from RxNorm (NLM); GPI from Medi-Span; GCN / HIC / AHFS / legend from First Databank.
🏷️ RxNorm drug class
This medicine belongs to the Magnesium compounds class.
Drug family (ATC)
Magnesium compounds, Osmotically acting laxatives, Magnesium
Where does this data come from?
Therapeutic classes from RxNorm RxClass (U.S. National Library of Medicine) — Established Pharmacologic Class (FDA), ATC drug family (WHO) and mechanism of action, matched by this product’s RxCUI.
🏭 Manufacturer & labeler
LabelerMarlex Pharmaceuticals Inc.
FDA applicationM001 (OTC MONOGRAPH DRUG)
Labeler code10135
First marketedNov 2023
Product typeHuman Otc Drug
Portfolio2 products on file
The labeler markets the product; the application holder owns the FDA approval. They’re often the same company but can differ (e.g. a repackager or an authorized generic). A mailing address / phone appears here when the manufacturer includes it in the product’s FDA label (not all do).
Where does this data come from?
Labeler, application holder and registered establishment from the FDA openFDA NDC Directory and Drugs@FDA; address/contact from the product’s FDA label.
🩺 Clinical
Label name MAGNESIUM OXIDE 420 MG TABLET Ingredient Magnesium Oxide
📖 What it is MedlinePlus · NLM
Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some people use it as an antacid to relieve heartburn, sour stomach, or acid indigestion. Magnesium oxide also may be used as a laxative for short-term, rapid emptying of the bowel (before surgery, for example). It should not be used repeatedly. Magnesium oxide also is used as a dietary supplement when the amount of magnesium in the diet is not enough. Magnesium oxide is available without a prescription.
Read the full MedlinePlus article ↗📗 Our plain-language guide HelloPharmacist
- It depends on the product you have. Some magnesium oxide tablets work as an antacid — they help relieve acid indigestion and upset stomach. Other products are sold as a dietary sup...
- What is magnesium oxide actually used for?
- When used as an antacid, you shouldn't use the maximum dose for more than two weeks in a row unless your doctor is guiding you. The magnesium supplement form is meant for daily use...
- Can I take it every day, or is it just for when I have an upset stomach?
Patient education
Supplement & herbal interactions
Where does this data come from?
Plain-language summary from MedlinePlus (U.S. National Library of Medicine); supplement & herbal interactions and nutrient depletion data from the Natural Medicines database; our full guide is HelloPharmacist editorial content.
💬 Questions about magnesium oxide?
Ask a pharmacist →
Ask a licensed pharmacist directly — free, answered by our team.
💊 What it looks like
Color
white
ShapeRound
Size11 mm
ScoringNot scored
One label can cover several strengths, so colors may be combined — always confirm a loose pill against the dispensed prescription label or a pharmacist.
Where does this data come from?
Physical description (imprint, shape, color, scoring, coating) from this product’s FDA Structured Product Labeling (SPL), mirrored from DailyMed / openFDA.
🧪 Inactive Ingredients / Excipients
Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.
💡 Tap an ingredient (hover on desktop) to see what it is and why it’s used.
-
UNII M28OL1HH48
Croscarmellose sodium is a plant-based substance derived from cellulose. It acts as a disintegrant, helping tablets and capsules break down quickly in the digestive system so the medicine can be absorbed.
-
UNII OP1R32D61U
Microcrystalline cellulose is a purified form of cellulose, a natural fiber from plant sources. It acts as a binder and filler in tablets and capsules, helping hold ingredients together and give the medicine its shape and size.
-
UNII ETJ7Z6XBU4
Silicon dioxide is a naturally occurring mineral used as a glidant and anti-caking agent. It helps powder ingredients flow smoothly and prevents clumping during manufacturing and storage.
-
UNII 4ELV7Z65AP
Stearic acid is a fatty acid derived from plant or animal sources. It acts as a binder and lubricant in tablets and capsules, helping them hold together and flow smoothly during manufacturing.
4 inactive ingredients listed in the exact product block matched to this NDC.
The official label also statesColloidal silicon dioxide, Croscarmellose sodium, microcrystalline cellulose, stearic acid Magnesium oxide may help with magnesium deficiencies.*
Label-section wording can be broader than the structured product block and may mention additional formulation ingredients.
Where does this data come from?
Data sourced from official FDA Structured Product Labeling (SPL) via DailyMed —
ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.Inactive ingredient FAQ
Are inactive ingredients the same for every manufacturer?
No. Inactive ingredients can differ by manufacturer, dosage form, strength, and package / product version.
Why might an inactive ingredient be missing?
Some SPLs do not provide a complete structured inactive-ingredient list, and older or unusual labels may only include the information in narrative text.
Can inactive ingredients matter?
Yes. They can matter for allergies, intolerances, dyes, gluten / lactose concerns, preservatives, and formulation differences — but confirm with a pharmacist or the manufacturer when it’s clinically important.
💲 Pricing
A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.
| Price system | Per each | Per package |
|---|---|---|
| Retail pharmacies payNADAC · weekly | Not in the retail survey — common for institutional, discontinued, or low-volume packs. | |
| Medicaid paysCMS SDUD · 12 mo | No recent Medicaid claims on file for this NDC — rare and low-volume NDCs are suppressed in the public data. | |
| Medicare drug plans payPart D · quarterly | No Part D plan price is available for this NDC in our data. | |
ℹ️
No price is published for this exact package yet. CMS surveys NADAC per package size, so a different pack of the same drug often has one.
Where does this data come from?
NADAC (National Average Drug Acquisition Cost) is the CMS weekly pharmacy-acquisition-cost survey — what pharmacies pay. ASP (Average Sales Price) is the CMS Medicare Part B drug-payment file, published quarterly. Medicaid pays is computed by us from CMS State Drug Utilization Data (total reimbursed ÷ units, trailing 12 months) — gross of rebates and inclusive of dispensing fees, so it reflects what Medicaid paid, not an acquisition cost. Medicare drug plans pay is the median negotiated point-of-sale unit cost across plans listing this NDC in the CMS quarterly Prescription Drug Plan pricing files, before rebates. The VA pays is the federal contract price (FSS, and the statutory Big 4 ceiling where listed) from the VA National Acquisition Center pharmaceutical price file. All are free public government data; each measures a different payer, so the figures are not directly comparable.
🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| Magnesium Oxide 253 mg 00603-0213-21 | Endo | 100 tablets | $0.038 | — | Availability likely | — |
| magnesium oxide 420 mgthis 10135-0721-01 | Marlex | 100 tablets | — | — | FDA listed | — |
| Magnesium Oxide 420 mg 54738-0974-01 | Richmond | 100 tablets | — | — | FDA listed | — |
About this product: other versions of the same ingredient, strength and form are listed above, least expensive first, with FDA equivalence ratings where available.
Where does this data come from?
Equivalents are other NDCs of the same ingredient, form and route from the openFDA NDC Directory, ranked least-expensive-first by NADAC. Therapeutic-equivalence (AB) ratings come from the FDA Orange Book; biologics use the FDA Purple Book for biosimilar & interchangeable status.
⏳ Availability & generic status
🏛️
2023
On the market since
Nov 2023
📍
2026
Currently FDA-listed
3 years listed
🔒
·
No generic listed yet
brand only
ℹ️No FDA-approved generic found
We did not find an FDA-approved generic match for this exact strength, form and route.
Where does this data come from?
Patents and exclusivity from the FDA Orange Book (small-molecule drugs), refreshed from public FDA data. Generic launch timing is an estimate, not a guarantee.
🔬 Reported adverse events (FAERS)
Read carefully: FAERS reports are voluntary and unverified. Counts are not incidence, do not establish causation, are subject to reporting bias, and cannot be used to compare one drug to another. Shown for signal context only. Reports for Magnesium Oxide — the ingredient across all brands.
Top reported reactions
Age at onset
Reporter sex
Male · 43%
Female · 57%
Unknown · 0%
Serious outcomes
Reports over time (by year) — tap or hover for the count & year
Most recent year is provisional (FAERS lags ~3 months).
Where does this data come from?
Adverse-event reports from the FDA Adverse Event Reporting System (FAERS) via openFDA. FAERS reports are voluntary and unverified — counts are not incidence and don’t establish causation.
📦 Packaging — all sizes for this product
| Package NDC | Description | Marketing start | Status |
|---|---|---|---|
| 10135-0721-01 You're viewing this | 100 TABLET in 1 BOTTLE (10135-721-01) | 2023-11-01 | Active |
🧭 About this NDC listing & data coverage
Over-the-counter (OTC) product
What data is (and isn’t) available for this NDC — tap to expand
| NDC identity (package / product / labeler codes) | ✓ Available |
| Labeler | ✓ Available |
| Product & package description | ✓ Available |
| Marketing category & status | ✓ Available |
| Active ingredient / dosage form / route | ✓ Available |
| FDA label (SPL via DailyMed) | ✓ Available |
| Package photos | ✓ Available |
| Inactive ingredients (structured) | ✓ Available |
| NADAC pharmacy acquisition price (CMS) | — Not published for this NDC CMS publishes NADAC only for NDCs reported in its retail-pharmacy survey. |
| Orange Book / therapeutic-equivalence data | — Not published for this NDC Applies only to products approved under an NDA/ANDA; many listings are out of scope. |
| HCPCS J-code billing crosswalk | — Not published for this NDC Most self-administered / retail products have no J-code — that is normal. |
| Medicaid utilization (CMS SDUD) | — Not published for this NDC CMS reports utilization only for NDCs with Medicaid claims above its privacy threshold. |
“Not published” reflects what the public FDA / CMS / NLM sources provide for this exact package code — it is a property of the data feeds, not a judgment about the product.
Questions about this listing
Is this NDC FDA-approved?
An NDC listing does not by itself establish FDA approval — the NDC Directory records that a product is listed with FDA, not that it was reviewed and approved. This listing's marketing category is "Otc Monograph Drug". Products approved under an application carry an NDA, ANDA, or BLA number.
Why is there no price listed?
The pricing shown on our NDC pages comes from CMS NADAC, a voluntary survey of retail community pharmacy invoices. CMS does not publish a NADAC for every NDC — packages outside the retail survey (institutional and hospital products, bulk packages, discontinued items, and many OTC items) may never receive one. A missing price reflects the survey's scope, not this product's actual cost, and does not mean the product is free or unavailable.
Is the NDC printed on the package the same as the 11-digit billing NDC?
Yes, they identify this exact package in different formats. The FDA registers it as 10135-721-01, which is what is printed on the packaging and shown on DailyMed. Insurance claims use a fixed 11-digit 5-4-2 format, so the short segment is padded with a leading zero: 10135-0721-01, written without dashes as 10135072101. The Identity section at the top of this page lists every form of this code.
What do the three segments of this NDC mean?
In 10135-0721-01, the first segment (10135) is the labeler code FDA assigned to Marlex Pharmaceuticals Inc.; the middle segment (0721) identifies this specific product — its ingredient, strength, and dosage form; and the last segment (01) identifies this exact package size and type. Together they name one specific package of one specific product.
Is this package still being marketed?
Yes, per the latest FDA NDC Directory data on this page: this package is listed as actively marketed, with no marketing end date reported by Marlex Pharmaceuticals Inc.. Listing status can change — the directory data on this page refreshes weekly.
Who lists this product with the FDA?
Marlex Pharmaceuticals Inc. is the labeler of record for this NDC — the company under whose FDA-assigned code the package is listed. The labeler may be the manufacturer itself or a distributor marketing the product under its own code.
Do I need a prescription for this product?
This NDC is listed with FDA as an over-the-counter product, so it does not require a prescription. Follow the package directions, and ask your pharmacist if you are unsure whether it is right for you.
This page identifies an FDA-listed package (the NDC) and reports public regulatory and pricing data about the listing. It is reference information, not a medical recommendation — talk to your pharmacist or prescriber about your own medication.
Where does this data come from?
Listing facts (marketing category, packager status, marketing dates) from the FDA openFDA NDC Directory; label availability from DailyMed; pricing coverage from CMS NADAC; equivalence scope from the FDA Orange Book.
📄 FDA label — Drug Facts FDA SPL
The complete FDA label for this product — the official Drug Facts labeling, verbatim, section by section. Jump with a chip, search within the label, or expand everything.
🎯 Indications and Usage
⏱️ Dosage and Administration
⚠️ Warnings
🧪 Active Ingredient
🧪 Inactive Ingredients
🎯 Purpose
🎯 Indications and Usage ▾
SUGGESTED USE As a dietary supplements, adult take one (1) tablet daily preferably with food or as directed by your healthcare practitioner.
⏱️ Dosage and Administration ▾
Supplement Facts Serving Size 1 Tablet Magnesium (as Magnesium Oxide) Amount per Serving 253mg % Daily value 63%
⚠️ Warnings ▾
CAUTIONS If you are pregnant, nursing, taking any medications or have any medical condition, consult your doctor before use. If you have any kidney disease, take only under the supervision of a doctor. Discontinue use and consult your doctor if any adverse reactions occur. Keep out of reach of children.
DO NOT USE IF IMPRINTED SAFETY SEAL UNDER CAP IS BROKEN OR MISSING.
🧪 Active Ingredient ▾
ACTIVE INGREDIENT (In each tablet) Magnesium Oxide 420 mg
🧪 Inactive Ingredients ▾
Other Ingredients Colloidal silicon dioxide, Croscarmellose sodium, microcrystalline cellulose, stearic acid Magnesium oxide may help with magnesium deficiencies.*
🎯 Purpose ▾
Purpose Dietary Supplement
No label section mentions that — try another word, or open the full label on DailyMed below.
Source: FDA Structured Product Labeling, mirrored from DailyMed / openFDA.
Prefer the government’s original formatting? View this label on DailyMed ↗
For educational and professional reference only — not medical advice. Pricing reflects published
NADAC and CMS ASP (free public data) and may differ from your acquisition cost; always verify before billing or dispensing.